In #20 on the countdown, we get "A Christmas Riddle" from Batman and Robin Adventures #3 by Paul Dini, Ty Templeton and Rich Burchett.
In this story, the Riddler breaks into a Gotham City club at Christmas time and announces to the world that he will prove that some of the members of the club are really Batman and Robin.
What I really love about this bit is that Dini cleverly posits that Gotham City is so messed up that there are MULTIPLE candidates for Batman and Robin at the club...
Of course, the whole thing is a diversion for a theft (sort of like Riddler's ode to that great Christmas story, Die Hard) and when the real Batman and Robin show up (Bruce was not part of the club), he burns down a CHristmas Tree to slow them down, but they eventually catch him.
The relative lack of "Christmas" in the story reflects in this otherwise top-notch tale ranking fairly low on the countdown.